This invention relates to improvements in press forming method and apparatus by which a disk-shaped workpiece that has been bent is press-formed so as to be formed into a convex shape or a concave shape.
Hitherto, various types of press forming apparatuses are proposed and put into practical use. For example, the press forming apparatuses are used for forming a cover for a torque converter adopted in an automatic transmission. The cover is formed cup-shaped and has a cylindrical flange section whose one end is connected to a bottom section having an annular convex section. In order to form such cup-shaped products, a press forming is accomplished under combination of a plurality of single action press dies, as disclosed in Japanese Patent Laid-open Publication No. 2001-314921.